The role of nanoparticle synergies in the enhancement of the thermal conductivity and the flame retardant properties of polymer blends

Condensing boilers achieve very high efficiency levels by recovering heat from the flue gas before it is discarded. The recovery of latent heat from the water vapor in the humid gas is a very important part of the total heat recovery process. When biofuels are used, such as biodiesel, the condensate formed is corrosive - leading to the need for expensive alloys in the heat exchanger. In order to develop biofuels as a practical alternative to fossil fuel for home heating applications, it is necessary to replace the metallic alloys in the condensing section of these boilers with polymeric materials. The requirements for selecting the polymer are fairly rigorous and cannot be satisfied by any polymer alone; the polymer must withstand relatively high temperatures (T~250C) and be resistant to degradation in the presence of the sulfuric acid environment found in condensates produced from conventional oil combustion. Furthermore, even though the polymer is not in contact with fire, its proximity to an open flame and to the ignition electronics found in boilers, building code regulations require that the materials must be flame retardant, and conform at least to UL94-V0 or V2 requirements. Since no single polymeric material can satisfy these criteria, the focus of this research was to develop organic-inorganic polymer blend nanocomposites, with multiple types of nanoparticle fillers, such as RDP coated montmorilonite clays, Halloysite nanotubes, graphene and carbon nanotubes which in combination are used to tailor the mechanical, chemical, and thermal properties to meet the specific requirements for optimal boiler construction.